Hi, thanks for contributing to Akira.

A couple of general guidelines to follow:

• If your PR is a still a work in progress, open it as a Draft PR. I updated it already so no problem for now.
• Don't write that a PR fixes an issue if that issue doesn't have a 1-to-1 relationship with the PR. In this case, you're stating that this PR fixes the Beta Whishlist, but that's incorrect.

Unfortunately, this is not the right approach.

You're assuming that the items to paste are those currently selected. That's not always the case.
You're limiting the copy/paste to 1 item at a time, but that's not scalable and should account for all selected items, therefore, this PR should be postponed after the multiselect is implemented.
With this approach you will not properly inherit all the attributes of the duplicated item (colors, borders, rotation, etc.).
You're currently reaching properties and methods by going through the parent->child hierarchy of all the classes, which is cumbersome and not scalable. You should use events for that.

Thanks again for your contribution, but I recommend to spend a little bit more time in trying to get comfortable with Vala before submitting a PR.
Also, Akira has a fairly complex code base, so you should get yourself acquainted with it before submitting a PR to be sure you're following the same paradigms and architecture.

Another couple of fundamental things to consider:

• When copying, the cached elements should belong to the App and not the Window, so users can copy a shape from a window and paste it in another.
• When pasting, we need to detect what the user has saved in the clipboard and handle those cases (images, svg icons, text, etc.)